The invention relates to a circuit arrangement for controlling the output amplitude of a high-frequency power amplifier with maximum possible HF power, including a control circuit wherein an actual value signal is generated from the output amplitude using a peak value rectifier, the actual value signal is compared to a desired value signal, a control signal is generated from the actual value/desired value comparison, and this control signal is used to control the output amplitude in accordance with a predetermined value.
The invention is used, for example, for temperature compensation for power amplifiers with a pulse power of approximately 10 Watt for the GHz range (X-band, 8 GHz to 12 GHz). The invention is, however, not limited to this frequency band as well as this performance class.
Such power amplifiers are needed, for example, in radar technology as transmitting amplifiers in transmitting/receiving modules (T/R modules) for phase-controlled antennas. With such T/R modules, the output signal for the power amplifier generally is supplied directly, in particular without a phase and/or an amplitude actuator, to a transmitter or radiator element. For turning and/or forming of the transmitting directional diagram for such an antenna, it is necessary that phase and amplitude states, that are preset as exact as possible, are maintained between the waves emitted by neighboring radiator elements. If a plurality of such T/R modules are used for such an antenna, for example, several thousand, then it is obvious that a high amount of measuring, calibrating as well as balancing is necessary to adjust and/or check the required phase and/or amplitude states. Each T/R module must furthermore incorporate in an unfavorable way the required measuring as well as adjustment options (structural components). Among other things, these have the disadvantage of being susceptible to interference themselves and are not cost-effective.
It is therefore the object of the invention to provide an arrangement of the general type mentioned above, which permits an exact control of the output amplitude of a power amplifier, which can be manufactured with small dimensions, and which is mechanically robust, reliable as well as cost-effective, in particular for an industrial series production.